Submarine mine



Jan, 13. 1925. 1,522,906

H. B. PRATTv SUBMARINE MINE Filed Sept. lO. 1923 2 Sheets-Sheet l III IIILM mum "nu www ? y )1.444 22M vamp Jan. l3- 1925Y 1,522,906

H. B. PRATT SUBMARINE MINE Filed Sept. 10. 1923 2 Sheets-Sheet 2 5 y .4f /7 y Wg Patented dan. i3, i925.

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HARTLEY n. raam, or nAnaow-rN-runnnss, suenan-n Assienon To .VICKEns LIMITED, or wnsfriurnsrnn, Lennon, ENGLAND.

SUBVIARINE MEINE.

Application filed September To allie/om t may concern:

Be it known that l, HARTLEY BLYTH PRATT, a subject` of the. King of Great Britain, residing at Naval Construction lVorksI,l Barrow-in-Furness, in .the county of Lancaster, England", have invented certain new and useful lmprovementsin or Relating to Submarine Mines, of which the following is a specification.

Thisvinvention relates to submarine mines of the kind-that are fired by means of an.

' nected to the mooring cable, the variation in the tension of the latter acting against 'the resistance` of a spring and determining the position of the electric switch elements. ln order to maintain the parts watertight a flexible diaphragm, usually composed of rubber, has been located around the aforesaid shaft or equivalentl sliding member. in practice, this arrangement has been found te be objectionable on account of the fact that the hydrostatic pressure acting on the flexible diaphragm is lopposed to the buoyancy pull on the movable shaft, and at considerable depths, say 175 feet, the resultant effort is insufficient to ensure that the safety switch will remain closed when the mine is struck by a passing vessel. At greater depths the hydrostatic pressure acting on the diaphragm itself may even be greater than the buoyancy pull, in which case the safety switch will be maintained permanently open and the mine rendered inoperative.

According to the present invention the buoyancy pull upon the aforesaid sliding shaft or equivalent member is adapted to push the sliding shaft inwards instead of pulling it outwards while the flexible diaphragm which maintains the parts watertight is adapted to be pushed inwards instead of being pulled outwards.

The con- 10, 1923. Serial I\TQ.VG'61,754.V

tacts forming partof the electriccircuitlof the mine are also adapted :to be completedi. by the upward movementof. the slidingshaftl. instead of'fthe` downward movement ofthe?` said shaft. i

Owing to this arrangement the hydrostatic' pressure, when the mine is anchored'in' deep water, tendsto push the sliding .memberin-v wards and thus to keep `the switchclosedli: Consequently, thel :improved .mine vwill' lbe"A operative at any depthat. which itma'ybe anchored. The .power of thespringwhich controls the movementof thesliding shaftis only limited by Athat .which willvr permitgfthe buoyancy pull (unassisted by. hydrostatic? pressure) to keep the switch closed :when .the mine is laid near the surface.. Consequently',` and with a mine buoyancy of 40G/lbs or more a spring canbefitrted to exert-a thrust of 300 lbs which issuflicient to support the. weight of mooring rope and ensure that: the'. switch will be openedV andthe mine. kept safe if it should come adrift with 1,5001 feet of .94- circumference wire rope hanging free; ln the older construction of submarine mine the strength of the controllingspringcould not be increased withoutreducing the .working depth and withpthe spring which has heretofore been .used in` practice the switch;`

could only be maintained open when the mine was adrift with less than 4001 ft of ..94 mooring rope .hanging free as with any.`4 greater length of moo-ring rope the mine. still remained active when adrift. Further-l more and with the improved construction. above referred to the flexible diaphragm is pushed into operative position andrests on a dished metal plate. Thus the rubber is relieved lfrom tensiley stress and willf-last longer than diaphragms which, as in the existing standard type of mine, are unsupported against hydrostatic pressure when in. the operative position. y

According to a further feature of the present invention the detonator and primer are. maintained out of the relative. firing positionuntil `the mine has been launched .and anchored to the sea bed by a catch-which` is removed to allow the primer and detonator to take up the firing position by the upward movement of the shaft or equivalent'mem-k ber which serves to bringabout thecompletion of the electriccircuit.`

According to anotherfeature ofthe preseV f ent invention a delay actiondevice mayk alsoL be provided which prevents the tension in the niooringcable from providing thenecesr I said openingsto allow ingress of seay water f to the plug by the upward movement ot the sliding 'member ywhich controls the electric circuit. Y

In order that the said inventionmay .be clearly understoody andreadily carried into effect the'same will `now be described more rfully. with reference to the accompanyingl rdrawings which showby wayl of'examplear submarine. mine eimsti'ncted according to the present invention and in which AFigure 1 is apart sectional elevation yot the flotation chamber et a submarine mine..

Figure 2 'is' a detachexilelevation on a large sca-le ot" the tension controlled mechanism for making the electric circuit and aty theA ksame time allowing yther primer to be brought into 'firing Aposition lrelatively -to the detonator.

- `Figure 3 is a sectional elevation corre-y sponding to Figure 2, showing the parts reversed.

Figure 4 is a view at right angles to Figure 8, showing the casing for the primer and the electric detonator.

Figure 5 is a top plan view on a larger scale of the mechanism shown at Figure 2 and Figure 6 is a plan of the bottom of the iiotation chamber showing a releasing device which is manually operated to release the parts of the tiring mechanism prior to the mine being launched.

1 is the flotation chamber or mine proper. 2, 2 are the horn batteries. 3 is the chamber containing the main bursting charge. l is the slidably mounted primer and 5 is the electric detonator. The internal construction ot the detonator has not been shown as it forms no part oi the present invention; 6 is a push rod forming part ot' the aforesaid sliding member. 7 is a lever pivotally attafxhed to a bracket 7a on the lower part ot a hollow boa-like casting 14, one end of the said lever being connected to the, mooring cable 8 and the other end 9 bearing against a nut 10 mounted upon a screw thread on the lower extremity of the push rod 6. 11 is a split pin which extends through the lower part of the hollenT casting 14 and is normally7 positioned in a recess above the nut 10 so as to restrainV its movement, the

said pin 11 formingparty cfa safety device.

drawn prior rto launching ot the mine so asy to release the tension controlled parts o'l the mine. f 13 is thediaphragm which serves to maintain `the parts watertight, the said diaphragm being located between the casting la andthe 'fmechani-sm'plate or support 21. Seawater isallowed free accessto ythe lchamber y1451 beneath the diaphragm through openings 15. @wing tothis arrangement the diaphragm 13 when the mine is launchexlk is subjected to the hydrostatic pressure of the kwater which presses it inwards againsta conical seating 13a. .The rubber will thus be relieved tromtensilestress and will last longer than diaphragme unsupported against .hydrostatic pressure when in operative Aposi-r tion. The yupperr part 1 of the push rodc 6, in theexaniple shown, is attached to a .hollowplunger 16 slidably mountedy within an extension 2lr ot' the mechanism plate 21 and within the said plunger a'helicalspring 17 is located. rfhe lower extremity of the plungerl has a screw theaded rpart l16'and is clamped to the flexible diaphragm 13 by a'nntf16by and awasher 16e. AThe plunger 16 .is attached to the kupper end kof the push rod 6, the rod 6 to this end being 'formed with `aprojt-bction 6which engages withinanoteh in the lower end of the plunger 16. The up-` rper part ofthe spring 17 is located within a can `18,-, which is attached by sleeve nuts l,

y19, 19 and bolts Q0, 2O tothe extension 21 of the mechanism plate 21. lt will be observed that one of the bolts 19 extends through an opening 22 in the plunger 16 and thus acts as a guide therefor. The plunger 16 is provided with a pair of lateral eXtensions 16a, 16a having insulated bushes 16e, 16C within which are located recessed electric contact pieces 16, 16b (see Figures 3 and 5). 23, 23 are spring controlled plungers which are mounted within casings or cylinders 23a bolted to the mechanism plate 21 and located contiguous to the recessed contact pieces 16", 16. 24, :24 are electric leads in circuit with the horn batteries and with the electric detonator and which are attached to the outer extremities ot the plungers 23, Q3. It will be clear that on account ot this arrangement and when the Contact pieces 16", 16b are positioned between the spring pressed plungers 23, 23 the electric circuit from the horn batteries through the detonator will be completed. Normally. however, the contact pieces 16", 16b are held out of engagement with the spring pressed plungers 23, Q3 until the tension on*v the mooring cable acting, through the pivotcd lever 7, raises the push rod 6 and moves the plunger 16 in an upward direction.

25 is the primer' casing which is cast integral'with the plate 21.

In Figures 2,`

Aif() ieefeoc 3, 4 ande the primerhas been: removed forY the/salie of' cleai'ness but asI will` bel clear nected to tilie'casing `at 27a andthe other end being attached to theztop of the trip lever at27b 4(Figure 2); When in this positionA theend of the trip lever projects in the path of movement of the slidingprinier 4 and normally retains the same in the raised position shown at Figure 1. When, however, tl1e' push rod 7 and consequently the plunger 16 is raisedand the spring 17 compressed owing to theitension exerted on the klever 7 bythe mooring cable 8 the boss 22 on the plunger 16 presses the trip lever 26 inwards against the'influence of the springs 27 and moves thesame out of the -pathof movement of the primer 4 so that-the lat-ter falls into fcontact ,with the'electric detonator 5. Should theuiiine break from its moorings the spring 17 will return the plunger 16 to its original position Vand thereby remove the contact pieces 16h, 16b out of contact with th'espringpressed plunger 23, 23. The electric detonator is placed in circuit with the electric horns by means of spring pressed plungei's 28, 28 bolted ,to the primer casing by insulated supports 28 the inner ends of the said plungers 28, 28 pressing against copper contactl pieces surrounding the -electric detonator.

rIhe auxiliary rsafety device for maintaining the parts out of action until the mine has been launched for a predetermined iiiterval ofttime, is constituted by a soluble" plug'l VApositioned'around the vlever 6 andv acted upon by a spring pressed plunger 32 which normally maintains the soluble plug in the position shown at Figure 3. On either side of the soluble plug 31 are rubber rings 33, 33. On the mine being launched and being anchored to they sea bed the tension on the mooring cable causes the end of the lever 7 to raise the push lever 6. The plunger 32 is also raised slightly against the resistance of its spring thereby bringing the soluble plug 31 opposite openings 35, 35 in the casting 14. The sea water thereupon acts on the soluble plug 31, and dissolves the same and thereafter the lever 6 is permitted to be raised (assisted if desired and as shown by the hydrostatic pressure acting on the diaphragm 13) to the extent which is necessary to bring the contact pieces 1Gb, 1Gb opposite the spring pressed plunger 23, 23 thus completing the electric circuit through the' detonatorr and simultaneously allowingfltheprimerfand detonatorto move into y:the relative firing position.

lhat claim'iand'fdesireto secureby Let-1v ters Patent of theUnited States is :-V

1. A submarine mine comprising an elec-VA tric circuit,-` contact devices which 'explode the mine `aut'omaticall'y whenstruckby a moving body, and a safety-device, controlled by the tension of the mooring cablewhiclr automatically makes or `breaksjthe electric iring'carcuit, said safety device comprising' f a switch-"element located within the mine-'lA casing,a movable switch elementwalso lo'- cated within the mine casing, means which maintain said `movable switch element out of contact with the other switch element when the mine is not anchored, a member which onv the mine being anchored moves automatically upwards -relatively to the mine casing and closes the firing circuit of the mine, a pivoted lever one-end of which acts upon 'said member, and a connection from ythe other end of said pivoted lever toi said mooring cable for'controlling the auto' matic movement of said member.

2. A submarine mine comprising a flota-v tionr chamber containing an' electric firing circuit, contact devices which explode the mine automatically when struck jby a movmine casing, movable switchingf-means also4 located within the mine casing, spring means tending to maintain said movable switchingmeans out of contact withtsaidY fixed switchingv means,` and a pivoted lever one end of whichis connected to the mooring cable and the other end of which bears upon said/movable switching means, said lever immediately the mine is anchored servingto aut'omatically'-lift said movable switching means into contact with said fixed switching y means and maintain said parts in this posimaintain said movable switch element out of contact with the fiXed switch element when the mine is not anchored, a member connected to said movable switch element which on the mine being anchored moves automatically relatively to the mine casing and closes the ring circuit of the mine, a pivoted lever, a connection from said pivoted lever to said mooring cable, and a delay action device which prevents the tension in the mooring cable from acting on said movable switch element until after a predetermined interval of time.

4. A submarine mine comprising an electric firing circuit, contactl devices which explode the mine automatically when struck by a moving body, and a safety device, controlled by the tension of' the mooring cable which automatically makes or breaks the electric firing circuit, said safety device comprising a switch element located within the mine casing, a movable switch element also located within the mine casing, means which maintain said movable switch element out of contact with the fixedV switch element when the mine is not anchored, a slidable member which on the mine being anchored moves automatically upwards relatively to the mine casing and closes the firing circuit of the mine, a pivoted lever one end of which acts upon said member, and a connection from the other end of said pivoted lever to said mooring cable for controlling the automatic movement of said member, a flexible diaphragm surrounding said slidable member which maintains the parts water-tight, a conical seating above said flexible diaphragm, said flexible diaphragm being adapted to be pushed upwards when the mine is anchored into contact with said conical seating for the purpose specified.

5. A submarine mine comprising an electric firing circuit, contact devices which eX- plode the mine automatically when struck by a moving body,A and a safety device controlled by the tension of the mooring cable which automatically makes or breaks the electric firing circuit, said safety device comprising a switch element located within the mine casing, a movable switch element also located within the mine casing, means which maintain said movable switch element out of contact with the fixed switch element when the mine is not anchored, a member which on the mine being anchored moves automatically upwards relatively to thel mine easing and closes the firing circuit of the mine, a pivoted lever one end of' which acts upon said member, a connection from the other end of said pivoted lever to said mooringl cable, a flexible diaphragm surrounding said member which maintains the parts water-tight, a conical seating located above said flexible diaphragm, said flexible diaphragm being adapted to be pushed upwards against said conical seating both by the hydrostatic pressure and by the buoyancy pull on the mooring cable for the purpose specified.

G. A submarine mine of the kind comprising a flotation chamber', a sinker, a mooring rope connecting said flotation chamber and sinlrer, a detonator and primer, means for maintaining said detonator and primer out of the relative firing position until the mine has been launched and anchored to the sea bed, a. sliding member, a pivoted lever connected to the mooring cable and acting on said sliding member, and means controlled by the upward movement of said sliding shaft due to pressure eX- erted by said pivoted lever for causing said detonator and primer to take up the relative firing position.

7. A submarine mine comprising a casing attached to the lower part of the mine, a soluble plug located within said casing, said casing being provided with openings through which water is allowed to enter and act on the soluble plug, a sliding member controlled by the tension on the mooring cable, and means controlled by the upward movement of said sliding member for bringing said plug opposite said openings so as to allow the sea water to act upon the same.

H. B. PRATT. 

